DESCRIPTION (Adapted from the Applicant?s Abstract): Cells of the renal medulla are highly specialized to function in the adverse environment of hyperosmotic stress. The laboratory of Dr. Steven Gullans (Sponsor) has developed two cell lines ideal for studying how cells of the renal medulla survive this harsh environment. The mIMCD3 and the hyperosmotically adapted mIMCD3 cell lines have been shown to portray gene expression induced by transcription factors that are sensitive to changes in the osmotic environment are not clearly understood. The specific aims of this proposal are: 1) To create a new hypothesis that delineates a cell?s programmed response to hyperosmotic stress by identifying all differentially expressed transcription factors and their induced downstream effector genes from time-dependent hyperosmotically stressed mIMCD3 cells; 2) Confirm that the hyperosmotically-induced transcription factors in Aim 1 are differentially expressed by separate northern and western analysis; 3) Recapitulate transcription signaling pathways induced from hyperosmotic stress by over expressing those hyperosmotically induced transcription factors via an inducible mammalian expression systen in mIMCD3 cells. This project will further our understanding of the molecular mechanisms involved in cell tolerance, adaptation and survival of stress, specifically hyperosmotic stress, and also provide the applicant with new research skills and experience required for a career as a successful independent investigator in a prominent academic medical center. The applicant has chosen the lab of Dr. Steven Gullans specifically for his established excellent reputation in renal physiology, specifically in terms of cellular adaptation to stress, his recent venture into the dynamic research of functional genomics and cDNA microarrays with the potential for gene therapy, the direct interaction of the lab involvement with human diseases, his success in mentoring post-doctoral researchers, and the location of his lab in a renowned academic medical center.